Google search and user filters

I have two machines - one with Ubuntu 14.04 and one with Windows 7.
I'm using Firefox with both.

Under Ubuntu I installed Adguard extension and under Windows I installed Adguard app. Same problem in both cases.

I'm using Google search page as my homepage in Firefox and I would like to remove top bar from Google search page.

I done that by adding new user filter (google.hr###gb > DIV.gb_Fb.gb_sc:first-child > DIV.gb_5.gb_sc.gb_e.gb_rc.gb_tc:first-child) and it is working but not for long. That top bar is back in a day. Than I add same filter again and that top bar is gone again. Everything is fine for one day but than it is back. I can remove it but it is coming back every time (always after a day or two).